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How to calculate pw from ve

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Old Apr 15, 2009 | 04:43 PM
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Gladstoneiroc's Avatar
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Car: 91 Camaro RS
Engine: 5.0L TBI (ebl inside)
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Axle/Gears: 3.42 lsd 10 bolt
How to calculate pw from ve

I tried searching, but what is the calculation for converting VE into pulse width in milliseconds?
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Old Apr 16, 2009 | 11:01 AM
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Re: How to calculate pw from ve

What are you trying to research/accomplish?

Seems the PW is the result of many multipliers of the VE table. Seems the VE table is a constant of sorts to be modified by ?? coolant temp comes to mind(OL) as well as IAT(CL) as well as PE when involked.
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Old Apr 16, 2009 | 11:10 AM
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From: Gladstone, Missouri
Car: 91 Camaro RS
Engine: 5.0L TBI (ebl inside)
Transmission: T-5
Axle/Gears: 3.42 lsd 10 bolt
Re: How to calculate pw from ve

For a physics class, I am trying to take those factors and be able to state a theoretical pulse width before showing the pulse width an oscilloscope.

I was trying to stick with VE table, PE, CTS tables to simplify.
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Old Apr 16, 2009 | 12:07 PM
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From: Chasing Electrons
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Re: How to calculate pw from ve

The PW equation that the (EBL) ECM uses is:

PW = BPC * ~AFR * ~T * MAP * VE (+- closed loop correction term)

It is based on ideal gas law. However, in the case of the inverse AFR and inverse temperature, there are tables that hold the actual values used in the calculation.

The $8D code does it a little differently. Directly calculating the mass of air in a cylinder (based on ~T and VE). Then applying the inverse AFR to that to get the mass of fuel required. Then factoring in the injector flow rate.

There is an article that explains SD well enough that you could put together a spread sheet for the calcs. OK, found the link:

http://marcintology.com/tuning/HowSp...ityWorks16.doc

This article explains how it is done along with showing the equations along the way. A real easy read, Marcin did a good job of writing it in an understandable form.

RBob.
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